Imaging Element Package Adhesive Slit Thermal Stress Relief

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Solution Overview

Problem

Existing imaging element packages face challenges in preventing peeling of the circuit substrate and displacement of connection positions due to thermal expansion differences between the circuit substrate and the transparent member, leading to reliability issues.

Innovation Solution

Incorporating a flexible substrate with slits in the adhesive portion that intersect with the direction of thermal expansion, surrounding the imaging element and forming a ventilation path to absorb and relieve thermal stress, thereby preventing distortion and improving connectivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If a transparent member is bonded to the circuit substrate to seal the opening, then the height of the imaging element package is reduced, but the circuit substrate may be distorted due to difference in linear expansion coefficients between the circuit substrate and the transparent member

Engineering Contradiction:

Improveheight of imaging element packageVSAvoiddistortion of circuit substrate

Core Design Contradiction:

Length of moving objectVSStability of the object's composition

Solution Approach 1:

The adhesive layer is segmented by forming slits that divide the continuous adhesive into multiple regions. This segmentation allows different parts of the adhesive to independently accommodate thermal expansion differences between the circuit substrate and transparent member, preventing overall substrate distortion while maintaining the sealing function.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The physical state of the adhesive is changed by introducing slits, transforming it from a continuous rigid bonding layer to a segmented structure with controlled flexibility. This parameter change enables the adhesive to absorb thermal stress through localized deformation at the slit regions, preventing circuit substrate distortion.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If the circuit substrate is bonded to the transparent member with adhesive, then the opening is sealed, but the adhesive interface may be peeled due to distortion of the circuit substrate

Engineering Contradiction:

Improvesealing of openingVSAvoidpeeling of adhesive interface

Core Design Contradiction:

Stability of the object's compositionVSReliability

Solution Approach 1:

The adhesive layer is divided into segmented regions by slits, which prevents stress concentration at the adhesive interface. Each segmented region can independently accommodate thermal expansion without causing delamination, thereby preventing peeling while maintaining the sealing function of the adhesive.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The slits are pre-formed in the adhesive layer to provide stress relief pathways before thermal expansion occurs. This beforehand cushioning allows the adhesive to accommodate future thermal stress through controlled localized deformation at the slit regions, preventing adhesive interface peeling.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Temperature

If the circuit substrate is distorted due to thermal expansion, then the position of external connection terminal may be displaced, but the secondary mounting reliability deteriorates

Engineering Contradiction:

Improvethermal expansionVSAvoidposition of external connection terminal

Core Design Contradiction:

TemperatureVSManufacturing precision

Solution Approach 1:

The slits segment the adhesive layer to create independent stress accommodation zones. This segmentation prevents the propagation of thermal expansion stresses across the entire substrate, isolating and containing any positional displacement to localized regions away from the external connection terminals, thereby maintaining manufacturing precision.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively enhances the reliability of the imaging element package by preventing peeling and displacement, ensuring stable connections and improved thermal management, resulting in a more reliable and durable camera module.

Implementation Method 1

due to a difference between linear expansion coefficients of the circuit substrate connected to the imaging element and a transparent member bonded to the circuit substrate, the circuit substrate may be distorted when the imaging element package is heated

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS10720459B2Imaging element package and camera module having a slit formed in an adhesive connecting a flexible substrate and another member to address differences in linear expansion coefficients

Publication Date: 2020.07.21 SONY SEMICON SOLUTIONS CORP

AI summary

The present technology relates to an imaging element package and a camera module capable of improving reliability. An imaging element package includes a flexible substrate, an imaging element connected to a first surface of the flexible substrate, and a member, bonded to a second surface of the flexible substrate opposite to the first surface with an adhesive, having a linear expansion coefficient different from the flexible substrate, in which in a portion of the adhesive, a slit is formed which intersects with a direction from the imaging element toward an end of the flexible substrate as viewed from a direction perpendicular to the flexible substrate. The present technology is applied to a camera module.